package com.feonix.common.util.mvc;

import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;

import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.AbstractHttpMessageConverter;
import org.springframework.util.FileCopyUtils;

public class DefaultStringHttpMessageConverter extends AbstractHttpMessageConverter<String> {
	public static final Charset DEFAULT_CHARSET = Charset.forName("utf-8");
	private final Charset defaultCharset;
	private final List<Charset> availableCharsets;
	private boolean writeAcceptCharset;

	public DefaultStringHttpMessageConverter() {
		this(DEFAULT_CHARSET);
	}

	/**
	 * A constructor accepting a default charset to use if the requested content
	 * type does not specify one.
	 * 
	 * @param defaultCharset
	 */
	public DefaultStringHttpMessageConverter(Charset defaultCharset) {
		super(new MediaType[] { new MediaType("text", "plain", defaultCharset), MediaType.ALL });

		this.writeAcceptCharset = true;

		this.defaultCharset = defaultCharset;
		this.availableCharsets = new ArrayList<Charset>(Charset.availableCharsets().values());
	}

	/**
	 * Indicates whether the Accept-Charset should be written to any outgoing
	 * request.
	 * 
	 * @param writeAcceptCharset
	 */
	public void setWriteAcceptCharset(boolean writeAcceptCharset) {
		this.writeAcceptCharset = writeAcceptCharset;
	}

	/**
	 * 类
	 * org.springframework.http.converter.AbstractHttpMessageConverter<java.lang.String>
	 * 中的 supports
	 */
	public boolean supports(Class<?> clazz) {
		return String.class.equals(clazz);
	}

	protected String readInternal(Class<? extends String> clazz, HttpInputMessage inputMessage) throws IOException {
		Charset charset = getContentTypeCharset(inputMessage.getHeaders().getContentType());
		return FileCopyUtils.copyToString(new InputStreamReader(inputMessage.getBody(), charset));
	}

	protected Long getContentLength(String s, MediaType contentType) {
		Charset charset = getContentTypeCharset(contentType);
		try {
			return Long.valueOf(s.getBytes(charset.name()).length);
		} catch (UnsupportedEncodingException unsupportedEncodingException) {
			throw new IllegalStateException(unsupportedEncodingException);
		}
	}

	protected void writeInternal(String s, HttpOutputMessage outputMessage) throws IOException {
		if (this.writeAcceptCharset) {
			outputMessage.getHeaders().setAcceptCharset(getAcceptedCharsets());
		}
		Charset charset = getContentTypeCharset(outputMessage.getHeaders().getContentType());
		FileCopyUtils.copy(s, new OutputStreamWriter(outputMessage.getBody(), charset));
	}

	protected List<Charset> getAcceptedCharsets() {
		return this.availableCharsets;
	}

	private Charset getContentTypeCharset(MediaType contentType) {
		if ((contentType != null) && (contentType.getCharset() != null)) {
			return contentType.getCharset();
		}
		return this.defaultCharset;
	}
}
